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Simplify the condvar a bit.

--- a/lib/thread/condvar+linux.myr

+++ b/lib/thread/condvar+linux.myr

@@ -10,58 +10,41 @@

 		_seq	: int32

 	;;

-	const mkcond	: (-> cond)

-	const condwait	: (cond : cond#, mtx : mutex# -> void)

+	const mkcond	: (mtx : mutex# -> cond)

+	const condwait	: (cond : cond# -> void)

 	const condsignal	: (cond : cond# -> void)

 	const condbroadcast	: (cond : cond# -> void)

 ;;

 generic Zptr = 0 castto(@a#)

-const Zmtx = 0 castto(mutex#)

-const mkcond = {

-	-> [._mtx = Zmtx, ._seq = 0]

+const mkcond = {mtx

+	-> [._mtx = mtx, ._seq = 0]

 }

-const condwait = {cond, mtx

+const condwait = {cond

 	var seq

+	var mtx

+	mtx = cond._mtx

 	seq = cond._seq

-	if cond._mtx != mtx

-		if cond._mtx != Zmtx

-			std.die("multiple mutexes used with cond var")

-		;;

-		mtxcas(&cond._mtx, Zmtx, mtx)

-		if cond._mtx != Zmtx

-			std.die("multiple mutexes used with cond var")

-		;;

-	;;

-	mtxunlock(cond._mtx)

+

+	mtxunlock(mtx)

 	sys.futex(&cond._seq, sys.Futexwait | sys.Futexpriv, seq, Zptr, Zptr, 0)

+	/* We need to atomically set the mutex to contended */

 	while xchg(&mtx._state, Contended) != Unlocked

 		sys.futex(&mtx._state, sys.Futexwait | sys.Futexpriv, Contended, Zptr, Zptr, 0)

 	;;

 }

-const condsig = {cond : cond#

+const condsignal = {cond : cond#

 	xadd(&cond._seq, 1)

 	sys.futex(&cond._seq, sys.Futexwake | sys.Futexpriv, 1, Zptr, Zptr, 0)

 }

 const condbroadcast = {cond : cond#

-	var m

-

-	m = cond._mtx

-	if m != Zmtx

-		xadd(&cond._seq, 1)

-		sys.futex(&cond._seq, sys.Futexrequeue | sys.Futexpriv, 1, Zptr, &m._state, 0)

-	;;

-}

-

-const mtxcas = {mtxp, old, new

-	-> xcas(mtxp castto(std.intptr#), \

-		old castto(std.intptr), \

-		new castto(std.intptr)) castto(mutex#)

+	xadd(&cond._seq, 1)

+	sys.futex(&cond._seq, sys.Futexrequeue | sys.Futexpriv, 1, Zptr, &cond._mtx._state, 0)

 }